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Magoo
was a big, playful Labrador retriever who often got
himself into some sticky situations. Usually, his
escapades were harmless. But one day, he managed to
snag a box of raisins from the pantry and ended up
eating an entire pound of the sweet treats. Other than
being exasperated by Magoo's behavior, his guardians
didn't think much about it. They knew that lots of
people shared grapes with their dogs and often used
raisins as training rewards. So it hardly seemed the
kind of emergency that required a call to the
veterinarian. In fact, if Magoo's parents had called
the ASPCA's Animal Poison Control Center (APCC) just a
few years ago, they would have been told not to worry
about it.
Through
the Grapevine
Enter
the APCC AnToxTM database, a computerized
system that contains nearly 500,000 animal-related
medical conditions and that enables veterinarians to
quickly identify toxic-substance exposures, recognize
clinical signs and administer proper treatment. By
tracking cases in this registry, similarities in
animal medical conditions nationwide can be logged and
syndromes can be identified.
Around
1989, the APCC began noticing a trend in dogs who had
eaten grapes or raisins: Nearly all developed acute
renal (kidney) failure. As more cases were reported,
enough data was generated in the database to help
veterinarians identify and treat dogs at risk. In all
of the cases, the ingredients for potential acute
renal failure were the same. Whether the ingested
grapes were purchased fresh from grocery stores or
grown in private yards didn't seem to matter, nor did
the brand eaten. And the ingested amounts varied
considerably, from over a pound of grapes to as little
as a single serving of raisins. The cases weren't from
any specific region, but instead came from across the
United States.
The
database showed that dogs who ate the grapes and
raisins typically vomited within a few hours of
ingestion. Most of the time, partially digested grapes
and raisins could be seen in the vomit, fecal
material, or both. At this point, some dogs would stop
eating (anorexia), and develop diarrhea. The dogs
often became quiet and lethargic, and showed signs of
abdominal pain. These clinical signs lasted for
several days -- sometimes even weeks.
When
medical care was sought, blood chemistry panels showed
consistent patternsHypercalcemia (elevated blood
calcium levels) was frequently present, as well as
elevated levels of blood urea nitrogen, creatinine and
phosphorous (substances that reflect kidney function).
These chemistries began to increase anywhere from 24
hours to several days after the dogs ate the fruit. As
the kidney damage developed, the dogs would produce
little urine. When they could no longer produce urine,
death occurred. In some cases, dogs who received
timely veterinary care still had to be euthanized.
Why
did the fruit cause the dogs to become ill? No one
knows. Suspect grapes and raisins have been screened
for various pesticides, heavy metals (such as zinc or
lead), and mycotoxins (fungal contaminants) and so
far, all results have come back negative. In the cases
where the grapes were grown in private yards, owners
confirmed that no insecticides, fertilizers or
antifungals had been used on the fruit.
"Raisin"
the Success Rate
Even
though the exact cause of the renal failure is
unknown, dogs who ingest grapes and raisins can be
treated successfully to prevent its development. The
first line of defense is decontamination. Inducing
vomiting in recent ingestions and administering
activated charcoal helps prevent absorption of
potential toxins. Dogs should be hospitalized and
placed on intravenous fluids for a minimum of 48
hours. A veterinarian should monitor blood chemistry
daily for at least three days following the ingestion.
If all blood work is normal after three days, it's
unlikely that kidney failure will occur. If a dog
shows evidence of renal failure, fluids must be
continued, and other medications should be used to
stimulate urine production. Some dogs may need
peritoneal dialysis, a process where the peritoneum
(the membranes surrounding the abdominal organs) is
used to filter waste products that are normally
filtered by the kidney.
Thanks
in part to the AnTox database, grape or raisin
ingestion can be easily identified and treated. Today,
a dog can make a complete recovery from this
potentially fatal condition.
Dr. Means is a veterinary
toxicologist at the ASPCA's Animal Poison Control
Center in Urbana, Illinois
http://www.aspca.org/site/PageServer?pagename=grapes
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